When Nancy Daly was helping to care for her late mother, who had Alzheimer’s disease, the stress was so great that she would often shut herself in a bathroom and cry into a towel. For more than two years, Daly regularly flew from her home in California to her mother’s in Maryland, eventually to no recognition. “It was as if my entire childhood was erased, when she did not know me,” says Daly, 59. “But I had to grit my teeth and bear it. It was my job to be there.”